EU Enlargement Commissioner Olli Rehn told reporters in Brussels after meeting with Bosnian officials that "constitutional evolution" was extremely important for Bosnia to make progress in its aim of joining the EU.

Rehn said the complicated structures devised to provide a balance of power between the three communities in Bosnia -- the Serbs, Croats, and Muslims -- are now inappropriate and could hinder talks with the EU.

Rehn said the EU is looking for a stable partner who could make decisions during negotiations, something Bosnia's current constitution makes difficult.

Bosnia is due to start "stabilization and association agreement" talks with the EU next month, a step on the path toward membership talks.